Endocannabinoids are released in the brain in response to synaptic activity and they interact with presynaptic receptors in a retrograde fashion to inhibit release of transmitter. They play key roles in modulating signaling between neurons. As with most other neurotransmitters, the termination of endocannabinoid action is thought to involve a transport activity that mediates reuptake into cells. Several putative inhibitors of reuptake have been shown to modulate endocannabinoid signaling, suggesting that the transporter may be an important target for gaining an understanding of endocannabinoid actions as well as for potential therapeutic applications. However, there is a great deal of controversy and a number of conflicting accounts concerning the mechanism and molecular basis of endocannabinoid transport. Because of this, we propose to use a novel fluorescent cannabinoid substrate as a selective tool to study endocannabinoid transport. This will allow us to 1) study the mechanism and kinetics of transport, 2) determine its spatiotemporal distribution in brain, and 3) to identify it by molecular cloning. Characterization and identification of the transporter will provide new strategies for developing potential therapeutic agents that modulate endocannabinoid levels for a wide range of applications including analgesia, anti-emesis, hypertension, and neurodegeneration. PUBLIC HEALTH RELEVANCE: Endocannabinoids produced in the brain interact with specific receptors to modulate signaling between neurons. As with most other neurotransmitters, the termination of endocannabinoid action is thought to involve a transport activity that mediates reuptake into cells. Because the molecular basis of endocannabinoid transport is unknown, we propose to use a novel fluorescent cannabinoid to 1) study its functional properties, 2) to determine its locations in the brain, and 3) to identify it by molecular cloning. Characterization and identification of the transporter will provide potential therapeutic strategies to modulate endocannabinoid levels for a wide range of applications including analgesia, anti-emesis, hypertension, and neurodegeneration.